The present invention relates generally to paint mixing machines and, more particularly, to pigment nozzles, by which pigment is controllably added to a paint container to alter the color of the paint.
Most hardware, paint, and general discount stores that sell paint provide it in a wide variety of colors. Because it is highly impractical to offer pre-mixed paint in thousands of colors, these stores stock paint in several base colors and finishes and provide samples or chips of available colors. By selectively adding pigments of up to a dozen or more colors to the base paint, it is possible to provide the customer with the exact color he or she desires.
Formerly, the adding of pigments was accomplished by consulting a formula associating ratios of different pigment colors with the selected sample, manually measuring the pigment, and mixing the pigment into the base color. This method is undesirable insofar as it requires a great deal of manual labor and exactitude in measurement (lest the final color be wrong and the paint wasted), and in high-volume sales operations, the mixing was too time-consuming for impatient customers.
Consequently, the solution has been to utilize an automatic pigment dispensing machine. A set of individually pumped reservoirs of pigment of differing colors is typically connected to a set of valves which, under microprocessor control, direct appropriate amounts of pigment through pigment tubes to a nozzle. A can of base paint is placed under the stationary nozzle. The machine, having been programmed to dispense the proper amount of each pigment, is activated and the pigment is then directed through the nozzle to the paint can. The paint can is capped and agitated, which thoroughly mixes the pigment throughout the base paint and produces paint of the desired color.
There are several attendant problems with the conventional automatic pigment dispensing machine. First, the nozzle is generally exposed to the air when the machine is not in use. If left uncovered and allowed to dry, the nozzle must be cleaned frequently so that a full flow of pigment through the tube is possible. In order to reduce the amount of cleaning that is necessary, it is helpful to utilize a nozzle cap, which is removable from the nozzle either manually or automatically, and which contains a wet sponge. The sponge, in turn, provides the nozzle with a moisture source to keep the nozzle wet over a longer period of time.
Second, the nozzle (and, more particularly, the pigment tubes located within the nozzle) inevitably requires cleaning to remove blockages. Because the pigment tubes are typically only loosely held within the nozzle so as to permit easy removal if replacement is necessary and because conventional retaining means tend to bind the tubes and restrict pigment flow, the removal of blockages, typically performed with an elongate member such as a wooden toothpick or a straightened paper clip, can result in the tube being inadvertently removed from the nozzle or mis-seated within the nozzle at an improper depth. This mis-seating can result in the tube touching the sponge, which causes smearing of the pigment onto and contamination of the sponge, or in the tube failing to extend far enough through the nozzle, which may prevent the proper amount of pigment from being placed into the base paint and result in improper mixing and wasted paint.
Third, because the nozzle is held stationary above an alcove for the paint can, it is difficult to align the paint can directly under the nozzle, particularly when the paint can is of a small size.
What is needed, therefore, is a paint mixing apparatus that includes a cappable nozzle, which retains the tubes against accidental displacement without undue pinching or flow restriction, and which nozzle is movable from a capped, dormant position, to a dispensing position so as to permit easy alignment of the paint can under the nozzle dispensing position.
In accordance with the above-described need, the object of the present invention is to provide for a means by which the pigment tubes in a paint mixing machine may be easily retained within the nozzle against accidental displacement, either during cleaning or movement of the nozzle, in which system the nozzle is movable between a dormant position and a dispensing position to permit the paint can to be more easily aligned with the nozzle dispensing position.
In order to meet this object, the present invention includes a nozzle comprising an array of holes each having a diameter sufficiently large to accommodate a pigment-conducting tube therein, the array being arranged to form a compact outlet for pigment. The invention further includes a first lock plate that is attachable to the nozzle and includes a first array of apertures that are arranged similarly to the holes in the nozzle, such that each aperture has a diameter sufficiently large to accommodate a pigment-conducting tube therein. A second lock plate is likewise attachable to the nozzle and includes a second array of apertures as in the first lock plate, arranged similarly to the holes in the nozzle. The first and second lock plates each include a pair of screw holes, through which a screw (or other appropriate means) may be used to attached the lock plates to the nozzle once the tubes have been placed through the lock plates and into the nozzle. These first and second lock plates are virtually identical, but they differ in a key respect. When the edges of the lock plates are aligned, the apertures in the plates are likewise aligned and permit a tube to be inserted therethrough, while the screw holes are offset. When the screw holes are aligned to permit attachment of the plates to the nozzle, the apertures are slightly offset, which serves slightly to deform any pigment tubes placed therethrough such that displacement of the tubes from the nozzle is substantially prevented.
In order to facilitate the attachment, the screw holes have a substantially greater diameter than the screw, but a washer having an outer diameter substantially equal to the screw holes and a beveled outer edge is inserted into the screw holes such that, as the screw is driven into the nozzle, screw holes are forced into alignment. In order to provide relief to the pigment tubes as they are retained within the lock plates, each aperture may be provided with one or more notches on its circumference, which enables the tube to be retained while reducing the flow restriction on the tube.
Because the pigment tubes are retained within the nozzle, the nozzle may be made movable between a dormant position and a dispensing position, thus permitting more precise alignment of a paint can under the nozzle dispensing position. Such movement may be controlled manually or by a microprocessor.
The present invention also provides for a paint mixing machine comprising an individually pumped reservoir of pigment, a valve for controlling the flow of pigment through pigment tubes, and a nozzle substantially as described above. The valve and nozzle are mounted on a mounting plate, which is movable between a dormant position and a dispensing position. At the dormant position, the nozzle is positioned over a cap, which prevents drying of pigment within the pigment tube. An optional sight comprises a hole in the mounting plate of substantially the same shape as the nozzle, which sight is positioned in the mounting plate such that when the mounting plate is in the dormant position, the position of the sight is identical to the position of the nozzle when the mounting plate is in the dormant position. A microprocessor may be employed to control the movement of the mounting plate, valve, and nozzle, as well as the actuation of the valve. Advantageously and preferably, a number of like valves, reservoirs, and pigment tubes are provided and connected within the lock plates and nozzle, and all are individually controlled by the microprocessor.
Also within the scope of the invention is a method of retaining a pigment tube within a nozzle using a pair of lock plates each including pair of attaching locations and an offset aperture in a paint pigment dispensing apparatus, which method includes the steps of aligning the apertures of the lock plates, placing the pigment tube through the aligned apertures, inserting the pigment tube into the nozzle, aligning the attaching locations of the lock plates, attaching the lock plates to the nozzle, and creating an offset between the apertures to deform the pigment tube and substantially to prevent its removal from the nozzle.